The Fn key is locked

This article offers solution to fixing a frozen Fn key on a keyboard.
A locked Function (Fn) key may sound like a minor problem, but can be a bit troublesome for the user if they are not aware of the solution. It may happen that while typing letters, numbers are being displayed on your screen. To fix this, you need to hold down the Fn key to write normally. The command is different for an IBM system.